One of the challenges that faces designers of devices having user-engageable displays, such as touchscreen displays, pertains to providing enhanced functionality for users, through gestures that can be employed with the devices. This is so, not only with devices having larger or multiple screens, but also in the context of devices having a smaller footprint, such as tablet PCs, hand-held devices, mobile phone, smaller multi-screen devices and the like.
Due in part to the small size of some devices and touchscreens, the types and number “on-screen” gestures (e.g., gestures applied to a touchscreen) that can be provided by a particular device may be limited. Moreover, on-screen gestures may interfere with content presentations in some contexts, such as by occluding a video presentation or a portion of digital book a user is viewing. Alternative techniques such as camera-based tracking and gestures may be impracticable or cost prohibitive for some devices. Accordingly, traditional touch gestures and input techniques may limit users and/or may be insufficient in some scenarios, use cases, or specific contexts of use.